The invention relates to apparatus for changing bobbins on a spinning machine or the like. Preferred embodiments of this invention relate to open-end spinning machines with several spinning stations and with at least one bobbin changer movable relatively to the spinning stations.
It has been contemplated to employ bobbin changers for exchanging the winding spools on spooling machines and double twisting machines (two-for-one twisters), wherein these bobbin changers serve for the operation of several operating stations, i.e. spooling stations in case of spooling machines or twisting stations in case of twisting machines. For this purpose the operating stations and the bobbin changers can be moved relatively to each other; preferably the bobbin changers are mounted to be movable along the operating stations. In these devices, the provision is made that the production process of the respective machine is interrupted during the bobbin changing procedure.
It has also been contemplated to provide bobbin changers in connection with open-end spinning machines and to fashion these changers as mobile, automatically operating servicing devices (U.S. Pat. Nos. 3,791,126 and 3,820,730; DOS's (German Unexamined Laid-Open Applications) Nos. 2,306,907; 2,308,682; 2,312,609; and 2,347,783). These types of construction, intended for open-end spinning machines, have the basic idea in common that the spinning operation is not interrupted during the exchange of the bobbin for a tube or quill. This basic idea is likewise utilized in another type of structure (British Pat. No. 1,166,504) wherein each individual spinning station is associated with its own device for exchanging the bobbins for a tube.
In the conventional types of construction, the spun thread is subjected to special mechanical stresses during the bobbin-change step, resulting in the ever-present danger that a thread break occurs during this bobbin-change operation. Such a thread break then leads to considerable difficulties in the conventional constructions, since it is practically impossible in such a case to conduct a piecing operation automatically. If an automatic piecing step is to be carried out, a thread end to be wound off from the spool must be returned into the spinning turbine, attached to the fiber ring present therein, and then must be withdrawn again. However, this is impossible if the bobbin has already ejected and a new tube has been inserted, since this new tube does not have a thread which could be returned. In this case, it becomes necessary to conduct the piecing operation manually by operating personnel. Such manual piecing operations are connected with a considerable production loss. In the conventional types of structures, it is thus necessary to refine the mode of operation and make the mechanical construction so sophisticated that the danger of thread breaks during bobbin change is greatly reduced, even though it cannot be entirely avoided for the basic reasons set out above. Consequently, these devices require a complicated manufacture with a correspondingly high cost involved.
This invention is based in part on solving the problems of providing an apparatus of the type mentioned in the foregoing wherein the manufacturing expenditures are relatively low and yet the necessity of conducting manual operations is avoided with certainty. These problems are solved by preferred apparatus for preliminarily joining a thread section to a spool tube which is to replace a completed bobbin. This thread section is of a sufficient length to accommodate at least a one-time automatic piecing operation.
The above-noted preferred embodiments of the invention start with the consideration that the operating safety is increased by being able to conduct an automatic piecing operation at all times. The short-term loss of production by the arrest of the spinning station during the bobbin-change step does not result in an essential reduction in the degree of efficiency of the spinning station. On the other hand, the invention provides increased safety from disturbances which heretofore had to be eliminated by manual operations carried out by the operating personnel and consequently led to considerable outage times and impairments of the degree of efficiency.
Since it can happen under certain circumstances that an automatic piecing operation fails, so that it must be repeated, it is advantageous if the thread section or piece connected according to the invention with the tube to be inserted in the spinning station is wound about the tube in the form of a starting winding, wherein the latter is dimensioned so that it is long enough for a repeated piecing procedure. Even if the starting winding should have been used up by a larger number of failures during piecing, it is still unnecessary to carry out manual work, since in such a case the empty tube can be exchanged for a new one, which again carries a starting winding, so that more piecing attempts can be carried out. Since during the bobbin change, i.e. when the filled spool is exchanged against a tube provided with a thread end section, the spinning operation is interrupted, there is no need to consider the running spinning unit. The device of preferred embodiments of this invention can thus be realized by simple technical means.
To facilitate the further processing of the bobbin provided with a cop during the spinning process, it is provided to attach in or on the empty tube a thread reserve. Independently of whether the thread reserve is present in the form of a thread end in the tube bore or in the form of a starting winding on the tube, this thread reserve can already be used as the thread section for the piecing operation. However, it is especially advantageous and simple to provide the thread reserve in the form of a reserve winding on the tube, arranged outside of the spooling range. In this connection, the beginning of the thread should be positioned fixedly in the reserve winding so that it is accessible even after the bobbin has been finished.
To produce the thread section with the starting winding, a spooling device is provided which is arranged fixedly, preferably at a head end of the open-end spinning machine according to certain preferred embodiments of the invention. This spooling device is associated with a transfer unit for transferring the tube provided with the starting winding from the spooling device to the individual pirning stations, which transfer unit preferably includes a conveyor belt or a conveying box with corresponding loading and unloading devices.
Other preferred embodiments of the invention are contemplated wherein a spooling device is provided movable together with the bobbin changer; this spooling device providing a thread section forming a starting winding and optionally a thread reserve for the tubes to be transferred to the bobbin stand of the spinning station and having at least one auxiliary bobbin from which the thread is taken to form the starting winding.
In embodiments of spooling devices mounted to be stationary, as well as embodiments mounted to be mobile, the spooling device preferably includes thread guide means to establish a reserve winding on the tube laterally of the starting winding and also means to fix the beginning of the thread in position in the reserve winding. It is particularly advantageous to fix the beginning of the thread by overlapping during the formation of the reserve winding. For this purpose, the spooling device preferably comprises clamping means to clamp the thread in position at the end face of the spooling tube and for bending the beginning of the thread in a direction toward the reserve winding. An especially advantageous solution resides in that the clamping means for the tubes has a cap extending over the tube rim; which cap bends the beginning of the thread in the direction toward the reserve winding.
Particularly advantageous preferred embodiments, other servicing units are formed as a structural unit in combination with the bobbin changing apparatus. In such embodiments, for various servicing units, individual devices, such as, for example, the moving gear and the drive, need be present only in singular. Particularly preferred embodiments have the bobbin changing apparatus arranged above the other servicing units since in such a case different servicing operations can be executed simultaneously at the same spinning station, so that the outage time of this spinning station can be maintained at a relatively low value.
Especially advantageous further developments and embodiments of the invention are set forth in the following detailed description and the claims. In this context, one or the other of the solutions can be particularly suitable, depending on the structure of the machine or the construction of the manufacturing site where the machine is utilized. Additional features and advantages of the invention can be seen from the following description of the various preferred embodiments illustrated in the drawings.